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Re:Perseverance Rover lands on Mars [video] by tectonic on Thursday February 18, 2021 @03:07PM (#26184751)
You can also watch an EDL visualization in your browser: https://eyes.nasa.gov/apps/mars2020/#/home

And read about how it will use Terrain Relative Navigation to find a safe landing spot: https://www.jpl.nasa.gov/news/a-neil-armstrong-for-mars-land...

Perseverance is phenomenally complex, its Sample Caching System alone contains 3,000+ parts and two robotic arms. So exited for all the sciencing this nuclear-powered, sample-drilling, laser-zapping behemoth can do when it joins its friends on the only planet (known) to be inhabited solely by robots.

Edit: Percy is about to release its two 77 kg Cruise Mass Balance Devices (is this what NASA calls 'weights'?) to setup the right lift-to-drag ratio for entry. Mars InSight will be listening for the 14,000 km/hr impacts of these weights, providing useful calibration data. We wrote about this in this week's issue of our space-related newsletter, Orbital Index - https://orbitalindex.com/archive/2021-02-17-Issue-104/

Re:Perseverance Rover lands on Mars [video] by michaelwilson on Thursday February 18, 2021 @08:59PM (#26188584)
It turns out that they took 640lbs (!) of weight to mars to be tossed off at various points during EDL. The video is worth watching if you'd like some more of the nitty-gritty behind the process: https://www.youtube.com/watch?v=W0NakShgbHY
Re:Perseverance Rover lands on Mars [video] by lopis on Friday February 19, 2021 @04:03AM (#26191043)
Note: that's 290kg in NASA units
Re:Perseverance Rover lands on Mars [video] by nroets on Saturday February 20, 2021 @09:34AM (#26204344)
And knowing the difference is an important part of rocket science:

https://www.simscale.com/blog/2017/12/nasa-mars-climate-orbi...

Re:Perseverance Rover lands on Mars [video] by jessriedel on Friday February 19, 2021 @01:49AM (#26190433)
Great video! I am also surprised by the fact that they bring that much mass just to jettison. In theory they could mounted some of the useful mass on a slider/rail system to achieve the necessary adjustment to the mass distribution without dropping mass overall, but apparently it wasn't worth the complexity/volume cost.

I'm sort of surprised we don't yet have ML powered "de-accent-ization". His french accent isn't hard to understand at normal speed, but when I set it to 1.5x or 2x speed it becomes hard to decipher in a way native speakers usually are not. If there was just a button (for him or me) to hit to tweak the sounds a bit to reduce the accent, I bet this problem would go away.

Re:Perseverance Rover lands on Mars [video] by _-___________-_ on Friday February 19, 2021 @04:03AM (#26191039)
I’m amazed that people still say things like “de-accent” as if there was such a thing as “no accent”. You are asking for a button that makes his French accent more like your own. It’s a separate thing from native vs. non-native speakers - there are plenty of native English speakers with accents that you would also find challenging.
Re:Perseverance Rover lands on Mars [video] by jessriedel on Friday February 19, 2021 @04:56AM (#26191331)
You are reading something into my comment that wasn't there in order to pick a boring fight. There is of course no such thing as no accent a priori, but there is such a thing as "accents understood by (vastly) more people" and "accents closer to the mean accent of native speakers". When I learn Russian, my English accent is not on the same footing as a Muscovite's; the intended notion of "de-accenting" the English accent on my Russian is obvious.

Consider responding to the substance of the comment instead.

Re:Perseverance Rover lands on Mars [video] by enriquto on Friday February 19, 2021 @06:50AM (#26192120)
> accents closer to the mean accent of native speakers

Notice that, for the case of English, most speakers are not native, by a huge margin! Native English speakers are a biased minority, and with a lot of variation within. Not sure that an "average native" accent is a useful concept at all. I, for one, tend to find most non-native English speakers vastly easier to understand than many native speakers.

Re:Perseverance Rover lands on Mars [video] by jychang on Friday February 19, 2021 @08:09AM (#26192721)
This is a dumb fight to pick. Dude just wants some ML software to figure out how to change accents.

Maybe he wants to change the accent to a Texas accent, or the Queen's english, who cares, it's the ML part that's interesting.

Re:Perseverance Rover lands on Mars [video] by jessriedel on Friday February 19, 2021 @12:15PM (#26195305)
> Notice that, for the case of English, most speakers are not native, by a huge margin!

I'm well aware, and this does not rebut any of my points.

> I, for one, tend to find most non-native English speakers vastly easier to understand than many native speakers.

That "many" native speakers in a language of hundreds of millions of speakers are hard to understand does not challenge the claim that a non-native accent brought closer to any native accent, much less the mean native accent, will for the large majority if listeners be easier rather than harder to understand.

Re:Perseverance Rover lands on Mars [video] by _-___________-_ on Thursday February 25, 2021 @05:28AM (#26261556)
What is the "mean native accent" for English? Would it be possible to somehow synthesise that? I'd love to hear what it sounds like!
Re:Perseverance Rover lands on Mars [video] by _-___________-_ on Thursday February 25, 2021 @05:29AM (#26261566)
I responded to the part of the comment that I had a response to, and I didn't mean any kind of hostility, much less to pick any kind of fight.
Re:Perseverance Rover lands on Mars [video] by aardshark on Friday February 19, 2021 @05:55AM (#26191720)
There is no such thing as "no accent". There is such a thing as a more neutral accent, or an accent more widely understood.
Re:Perseverance Rover lands on Mars [video] by craftinator on Saturday February 20, 2021 @01:55PM (#26206736)
Trash.
Re:Perseverance Rover lands on Mars [video] by stargazer-3 on Friday February 19, 2021 @03:39AM (#26190922)
I, for one, would be uncomfortable with AI removing my accent. I understand it's for other people to understand me better - and I am fine with AI-generated subtitles - but altering the way I speak would reduce the amount of "me" in ways I'm not fully ok with.
Re:Perseverance Rover lands on Mars [video] by omni on Friday February 19, 2021 @10:06AM (#26193932)
What's special about speech that makes this argument apply to speech alteration but not to subtitles? It's a tool to make you easier to understand, not to erase your person.
Re:Perseverance Rover lands on Mars [video] by hutzlibu on Saturday February 20, 2021 @06:47AM (#26203458)
Speech is more than articulating words. It is also about rhythm and melody and idealy also body language.

The way someone speaks is very unique ... and it is actually very, very important how you speak to bring your point across. Or ... to convince people.

A robot voice might present the best arguments, but it will very likely loose to a good speaker who can (literally) tune in to his audience.

Speech is a complex pattern of sound waves, containing much more information, than binary encoded words.

So if there was a ML tool to make people with strong accent more understandable, why not. But you can also numble without any accent.

And I can enjoy and understand certain people with strong accents much better than natives, because they are just good speakers.

And having subtitles is one thing, but changing their voice .. would require consent I believe. (unless you run the tool for yourself, but I believe parents point was, he speaks and then automatically a tool enhances his voice, I would not like that, too)

Re:Perseverance Rover lands on Mars [video] by jessriedel on Friday February 19, 2021 @04:48AM (#26191286)
You wouldn't need to use it on videos you produce if you don't want.
Re:Perseverance Rover lands on Mars [video] by throwaway316943 on Friday February 19, 2021 @09:58AM (#26193824)
Interesting, are you uncomfortable with the current option to increase or decrease playback speed?
Re:Perseverance Rover lands on Mars [video] by nippoo on Friday February 19, 2021 @10:36AM (#26194234)
No need to have a fancy all-new ML algorithm - stick a text-to-speech output on the auto-generated video subtitles and you can set it to whatever language you like.

If the speech recognition / subtitling algorithm can't understand the nuances of the language, that's going to be a problem anyway... accented pronunciation is so multidimensional, you're pretty much going to have to transcribe syllables/phonemes first...

Re:Perseverance Rover lands on Mars [video] by thamer on Friday February 19, 2021 @12:20AM (#26190050)
I was hoping someone would link this video, it describes the various phases with a ton of details that.

Some of the other videos on this channel are just as in-depth: the ones about the plumes/exhaust of rocket engines as well as star occlusions are incredibly detailed.

Re:Perseverance Rover lands on Mars [video] by rsj_hn on Friday February 19, 2021 @02:40AM (#26190626)
Thanks for introducing me to the French Space Guy! I am hooked.
Re:Perseverance Rover lands on Mars [video] by twic on Thursday February 18, 2021 @06:06PM (#26187099)
> Cruise Mass Balance Devices

They put those in to make the probe seem higher-quality. They got the idea from Beats headphones.

Re:Perseverance Rover lands on Mars [video] by jamiek88 on Thursday February 18, 2021 @07:19PM (#26187765)
Just to set the record a bit straighter and ruin your joke, those pics of beats with weights were knockoff beats from the flea market not real.
Re:Perseverance Rover lands on Mars [video] by lathiat on Thursday February 18, 2021 @07:55PM (#26188080)
Re:Perseverance Rover lands on Mars [video] by azernik on Thursday February 18, 2021 @07:33PM (#26187880)
We were doing that at Meraki back in the early 2010s (it turned out they were also useful as a heat sink and, because the metal was exposed to air, a radiator). Pretty sure Meraki got the idea from some Apple product or other.
Re:Perseverance Rover lands on Mars [video] by darkwater on Friday February 19, 2021 @04:07AM (#26191076)
Speaking of Meraki, I had an awful experience with those devices. Basically we were in building with TONS of other wifi networks around and Meraki network just went crazy from time to time until we fine tune it down to the channel for each AP. I mean, for something you pay $$$ to buy the devices and $$$ each month for the subscription is a pretty poor experience.
Re:Perseverance Rover lands on Mars [video] by rhodozelia on Saturday February 20, 2021 @01:55AM (#26202200)
Nortel and it’s predeccessors bell northern telecom used to put weights in the handsets so they had a nice feel to them.
Re:Perseverance Rover lands on Mars [video] by WJW on Thursday February 18, 2021 @04:55PM (#26186214)
> is this what NASA calls 'weights'?

Well no, the Cruise Mass Balance Devices are intended to Balance the Mass of the spaceship during Cruise conditions. That these Devices are single-part and constructed out of a single chunk of metal each should not be construed as merely being 'weights'. :)

Re:Perseverance Rover lands on Mars [video] by theelous3 on Thursday February 18, 2021 @09:26PM (#26188804)
What I'm getting from this, is that you can use weights to balance the mass of the spaceship during cruise conditions.
Re:Perseverance Rover lands on Mars [video] by numpad0 on Friday February 19, 2021 @12:27AM (#26190082)
Actually more like that you can eject weights to intentionally un-balance the mass of a spaceship so it'll glide rather than falling straight down.

Atmospheric drag force center of drag and center of gravity to line up on a same axis, which force the craft to fly slightly sideways if spacecraft isn't perfectly balanced. Done carefully, it leads to direction of flight being slightly sideways, which is awkward but basically same as having lift towards that direction. Add roll control thrusters into the mix, and you get a really crude glider, with fixed pitch force, zero yaw control and barely controllable roll. With JPL-class engineering, such a spacecraft will be capable of actively correcting landing location.

Re:Perseverance Rover lands on Mars [video] by jcims on Friday February 19, 2021 @03:09AM (#26190751)
It’s like hypersonic curling
Re:Perseverance Rover lands on Mars [video] by xarope on Thursday February 18, 2021 @09:47PM (#26188984)
Ships do this all the time (ballast), and anybody who's ever flown on a light aircraft or helicopter also knows the importance a pilot places on weight distribution.

I guess what's surprising is that they needed that much weight (140+kg seems like a lot?) and couldn't redistribute existing componentry; guess the knapsack algorithm wasn't good enough, or that they just couldn't break up enough pieces?

And yes, Cruise Mass Balance Devices sounds like the type of name a tired engineer would come up with to convince upper management...lol

Re:Perseverance Rover lands on Mars [video] by FredFS456 on Thursday February 18, 2021 @11:18PM (#26189654)
They can't redistribute existing componentry because of competing requirements: during cruise, the spacecraft needs to be balanced around the rotational axis (perseverance rotates at 2RPM in cruise). During re-entry, an asymmetric weight distribution is needed to generate lift.
Re:Perseverance Rover lands on Mars [video] by xarope on Thursday February 18, 2021 @09:50PM (#26188999)
Surely you mean: "What I'm getting from this, is that you can use devices to balance the mass of the spaceship during cruise conditions"...j/k
Re:Perseverance Rover lands on Mars [video] by Aeolun on Friday February 19, 2021 @03:57AM (#26191008)
Maybe they have both, and needed a name to distinguish the ejectable weights from the non-ejectable weights?
Re:Perseverance Rover lands on Mars [video] by rkagerer on Friday February 19, 2021 @07:02AM (#26192198)
Got it. Fancy weights.
Re:Perseverance Rover lands on Mars [video] by tectonic on Thursday February 18, 2021 @03:17PM (#26184894)
Also, InSight's SEIS seismometer is a true marvel: "We have been able to detect, at about 10 hertz, displacement of the ground of the order of less than 5 picometers…which is a fraction of the size of an atom." — https://eos.org/features/a-modern-manual-for-marsquake-monit...
Re:Perseverance Rover lands on Mars [video] by peter303 on Friday February 19, 2021 @03:56PM (#26197934)
LIGO puts this shame with 10^11 better sensitivity.
Re:Perseverance Rover lands on Mars [video] by jvanderbot on Saturday February 20, 2021 @03:12PM (#26207490)
At sensitivity/gram insight wins. Per dollar probably not.
Re:Perseverance Rover lands on Mars [video] by spaetzleesser on Thursday February 18, 2021 @06:38PM (#26187400)
They should make km the default unit and not miles....
Re:Perseverance Rover lands on Mars [video] by boilerupnc on Thursday February 18, 2021 @08:04PM (#26188145)
NASA has experience in unit foul-ups. Mars Climate Orbiter is the $125M poster project reminding everyone of the importance in having consistency in units.

"At 09:00:46 UT Sept. 23, 1999, the orbiter began its Mars orbit insertion burn as planned. The spacecraft was scheduled to re-establish contact after passing behind Mars, but, unfortunately, no signals were received from the spacecraft.

An investigation indicated that the failure resulted from a navigational error due to commands from Earth being sent in English units (in this case, pound-seconds) without being converted into the metric standard (Newton-seconds).

The error caused the orbiter to miss its intended orbit (87 to 93 miles or 140 to 50 kilometers) and to fall into the Martian atmosphere at approximately 35 miles (57 kilometers) in altitude and to disintegrate due to atmospheric stresses."[0]

[0] https://solarsystem.nasa.gov/missions/mars-climate-orbiter/i...

Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @07:51PM (#26188055)
Ever been on an airplane? Altitude was almost certainly measured in kilofeet.

As noted in other comments, NASA (like the rest of the United States [1]) does use the metric system.

But it doesn’t matter. Nothing about the metric system makes it uniquely suitable to landing on Mars. Or space travel in general. What matters is a consistent standard.

Internally NASA could use Armstrongs. Where 1 is the weight or height of Neil Armstrong at KSC on July 16, 1969 at 13:32:00 UTC. It doesn’t matter. As long as it is consistent.

[1]: https://en.m.wikipedia.org/wiki/Metrication_in_the_United_St...

Re:Perseverance Rover lands on Mars [video] by Melkman on Thursday February 18, 2021 @09:21PM (#26188761)
Consistency is not the only value of a system of units. Convenience is also of importance. And that is where the metric system shines. Having all measures of a unit in multiples 10 combines perfectly with our decimal calculations. Having as few as possible magical numbers to convert and combine between units makes making mistakes harder. How many calories in kinetic energy has a pound going 10 miles per hour ? I know a kilo going 10 meters per second has 50 joules of kinetic energy without looking up anything and doing the calculation in my head.
Re:Perseverance Rover lands on Mars [video] by killjoywashere on Thursday February 18, 2021 @10:01PM (#26189097)
Can’t talk to the statute mile, but the nautical mile is sublime: one minute of latitude. The amount of math you can do in your head with a system with so many factors of 2, 3, and 5 is truly amazing.
Re:Perseverance Rover lands on Mars [video] by danaliv on Thursday February 18, 2021 @11:07PM (#26189564)
Also the average of one minute of arc on a great circle route, which was the real handy thing about it at sea.
Re:Perseverance Rover lands on Mars [video] by killjoywashere on Thursday February 18, 2021 @11:39PM (#26189824)
Yes, meridians (on which latitude is measured) being a special case of great circle routes that happen to pass through the poles. That said, as a practical matter, you are more frequently contemplating a chart of smaller scale than "globe" so you're usually counting up distance between fixes, or distance to next turn in a harbor, or some such thing, where you have a compass in hand and just need to set the compass to the length of a mile. The nearest latitude tick marks are quite handy for that.
Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @10:16PM (#26189194)
I'm not aware of any tricks to make mile calculations easier but the fractional scale common with the inch is very useful for real-world mental calculation and practical exchange. Effectively everything is powers of two. Got something between 1/4 and 1/2 inch? Great, use 1/8ths. It's three. Not close enough? How about five 16ths? It infinitely scales to provide another unit that is suited to the measurement at hand. In some contexts you might just say you pick the closest 1/8th. In others you might use 32nds. You can use the same measuring devices to agree on an ad-hoc standard that everyone understands.

But with the metric system you only really get cm (too coarse) and mm (too fine) but you don't get something like 9/16 so you can't "work in 16ths" and have everything be whole units again.

Adjusting HVAC in degrees-C is infuriating to my Fahrenheit sensibilities. 20C is cold, 22C is hot. 21C is probably ok but really I want something like 20.5C. The comfortable range for a room is 3-5 whole units of F, but requires a bunch of fractions in C that you may not even have available on your thermostat.

Sure, converting between units is easy in the metric system. That doesn't make it the best thing to use all the time. Hell, the idea of thousandths of an inch is used commonly, so even the imperial system is base 1000 in some cases. But I've never seen anyone utilize the fractional scale with metric units, probably because the units are the wrong size for that to be useful.

Re:Perseverance Rover lands on Mars [video] by onion2k on Friday February 19, 2021 @01:14AM (#26190290)
But with the metric system you only really get cm (too coarse) and mm (too fine) but you don't get something like 9/16 so you can't "work in 16ths" and have everything be whole units again.

People who use metric units are perfectly happy rounding to the nearest 0.5cm or 0.25cm if that's what's needed, exactly as people do with inches. Why on earth would you imagine people use mm if something doesn't call for them?

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @03:33AM (#26190887)
But does anyone say 1/8th centimeter? Seems easier to just drop down to millimeters at that point. Which is fine, but it loses out on the convenience of fractions.
Re:Perseverance Rover lands on Mars [video] by onion2k on Friday February 19, 2021 @05:31AM (#26191541)
People do say things like 1.25mm, which is 1/8th of 1 cm.

Presumably someone who uses Imperial would say 5/128th inches if they wanted to describe something that's equivalent to 1mm?

Re:Perseverance Rover lands on Mars [video] by Evidlo on Friday February 19, 2021 @11:42AM (#26194915)
Most likely they would use mils/thou.

25mils ~ 1mm

Or 1/16in as others have said.

Re:Perseverance Rover lands on Mars [video] by Hextinium on Saturday February 20, 2021 @03:34AM (#26202621)
40 mils ~ 1 mm

1000 mils / 25.4 mm = 39.3

This simple fact still seems wrong to me somehow.

Re:Perseverance Rover lands on Mars [video] by Evidlo on Saturday February 20, 2021 @03:51AM (#26202729)
Brain fart
Re:Perseverance Rover lands on Mars [video] by sojournerc on Thursday February 18, 2021 @10:29PM (#26189293)
As an occasional woodworker and carpenter, I can tell you having evenly divisable (inch) measurements makes mental division a whole lot easier. It's just a case of using the right tool for the job.
Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @11:14PM (#26189621)
It’s unfortunate that fractional measurements and the base size of units get conflated.

Maybe metric users do use fractions and I just don’t hear about it. Is that table one and a quarter meters high?

Re:Perseverance Rover lands on Mars [video] by grecy on Thursday February 18, 2021 @11:33PM (#26189780)
We use millimetres. That table is 1250mm high.

If you're cutting it yourself, a precision of 1mm is finer than your saw blade or pencil line anyway, so it's plenty enough.

When I hear anything past about 1/8th of an inch my brain shuts down, and I give up.

Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @11:51PM (#26189895)
My argument is a mm is too fine in that situation. 1/8ths and 1/16ths are ideal when working at those scales.

In reality I use both systems all the time. It’s situational.

> When I hear anything past about 1/8th of an inch my brain shuts down, and I give up.

Realistically, same. 32nds don’t get used outside of some specialty wrenches. 16ths are a practical limit where other scales start to make more sense. Probably millimeters.

Re:Perseverance Rover lands on Mars [video] by cambalache on Friday February 19, 2021 @12:27AM (#26190085)
So 3 mm is a weird measure but 1/8 of an inch is just perfect? You are like those guys who say that Fahrenheit is better because it feels "more natural and obvious"
Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @12:44AM (#26190162)
I don’t understand why it has to be one or the other? Working in fractions is nice sometimes. Inches are a useful size for some situations. I find it easier to say that’s three eighths than 9mm because my ruler doesn’t have different marks for the factors of each mm mark.

I use both systems.

I do prefer Fahrenheit for HVAC (and weather) because it’s higher resolution and has reasonable values at human scales. Thermostats that lack half-degrees-c are never quite right IMO.

Re:Perseverance Rover lands on Mars [video] by cambalache on Friday February 19, 2021 @02:08AM (#26190512)
> I do prefer Fahrenheit for HVAC (and weather) because it’s higher resolution and has reasonable values at human scales.

So you are one of those, lol. There is nothing "less human" about 25 C than say 72 F. Nothing, it just happen to be the scale you are used to.Both are arbitrary.

> Fahrenheit for HVAC (and weather) because it’s higher resolution

99.99% of thermostats and thermometer in C had at least 1 decimal place. At usual "human temperatures" the difference in resolution between the scales is less than 2X, so even assuming only integer values, I am willing to bet against you in a double blind test that you cannot differentiate 68F vs 69F in an statistical significant way.

> I find it easier to say that’s three eighths than 9mm

Just because you are used to. Fractions are more complicated than integers, every elementary school program knows it.

So to summarize, the problem is not with the magnitude of the units which is arbitrary (a degree F and inches are not more human, logical or normal that a degree C or cm)the problem is with the convoluted way of the imperial system for multiples and submultiples of the base unit.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @03:12AM (#26190772)
“Human scales” meaning temperatures that won’t burn my skin or give me frostbite. 70 is nice. 60 is cool. 50 is cold. 40 is really cold. 80 is hot. 90 is really hot. 100 is potentially dangerously hot.

I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is really cold, 26.5 is hot, 32 is really hot and 37.7 is dangerously hot. It’s fine if you are used to it but I don’t really see a benefit.

I was in a hotel room in Japan that only had whole unit adjustments for the A/C. To get 20.5C I had to switch to Fahrenheit. I guess I was unlucky.

I find distances in metric and imperial perfectly usable and use both regularly.

As outlined in detail elsewhere in the thread there are advantages to working in fractions in some situations. Specifically when using a ruler or tape measure with different markings for 1/2, 1/4, 1/8 and 1/16. There’s no reason that has to be unique to inches, it just works out well in some cases.

Re:Perseverance Rover lands on Mars [video] by thiht on Friday February 19, 2021 @04:01AM (#26191029)
> I guess 20.5 is nice, 15.5 is cool, 10 is cold, 4.5 is really cold, 26.5 is hot, 32 is really hot and 37.7 is dangerously hot.

Or, you know, 20, 15, 5, 30 and 40 instead of the arbitrary decimals you chose to use to prove your point

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @05:00AM (#26191360)
Sure, you can pick even numbers in either scale that are awkward decimals in the other. I just prefer the ten degree bands of the Fahrenheit scale for these ranges.
Re:Perseverance Rover lands on Mars [video] by thiht on Friday February 19, 2021 @12:28PM (#26195462)
> I just prefer the ten degree bands of the Fahrenheit scale for these ranges.

To the identical 5 degrees range of the Celsius scale ?

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @02:12PM (#26196764)
It's not really identical though. Like I said, Fahrenheit is higher resolution at these scales so that is an advantage. It doesn't mean everyone should convert to F. Just that both systems have benefits. If I changed my perception of the world to C I wouldn't actually gain anything, personally, in the context of weather and HVAC.

If I need to take measurements while boiling water or making ice then I would probably use C.

Re:Perseverance Rover lands on Mars [video] by thiht on Saturday February 20, 2021 @04:58AM (#26203021)
It's exactly the same. The perception you have on Fahrenheit is exactly the same anyone using Celsius have, with multiples of 5 instead of 10
Re:Perseverance Rover lands on Mars [video] by mulmen on Saturday February 20, 2021 @04:06PM (#26207973)
Five is not equal to ten so no, it is not the same. That's the entire point.
Re:Perseverance Rover lands on Mars [video] by thiht on Sunday February 21, 2021 @05:07AM (#26212269)
Right.
Re:Perseverance Rover lands on Mars [video] by MereInterest on Saturday February 20, 2021 @08:47AM (#26204052)
Interesting comment on Fahrenheit, as I would say it has too much resolution for day to day use. A nice sunny day is in "the low 70s". A cold winter day is in "the high 20s". There is too much precision in the units to give an exact numeric value, so we round it to low/mid/high. That implies that the general unit we should be using is somewhere around 3 times larger than Fahrenheit degrees, because that is the size of the unit we use in speech anyways.
Re:Perseverance Rover lands on Mars [video] by mulmen on Saturday February 20, 2021 @03:39PM (#26207720)
Yeah it's personal opinion. Either scale works. Nobody gives weather reports to the public in kelvin.
Re:Perseverance Rover lands on Mars [video] by spaetzleesser on Thursday February 18, 2021 @11:26PM (#26189722)
People often say something is 1 and a half meters long. I don't understand how people can work with inch measurements. How do you divide 7"3/8 by 5? This seems a major pain.
Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @12:21AM (#26190053)
One and a half seems natural. What about something like a quarter meter? I guess that just becomes some number of centimeters?

> How do you divide 7"3/8 by 5?

Same way I divide 4.7625 cm by 5. With a calculator.

Re:Perseverance Rover lands on Mars [video] by flemhans on Friday February 19, 2021 @07:00AM (#26192184)
> I guess that just becomes some number of centimeters?

25, yes. It's not too hard to do the math.

> Same way I divide 4.7625 cm by 5. With a calculator.

That's roughly 0.95 right by intuition, but (7"3/8) / 5 doesn't come easy to me.

Re:Perseverance Rover lands on Mars [video] by chordalkeyboard on Friday February 19, 2021 @12:34AM (#26190116)
You multiply 7* 8 then add 3 and put that number over 8* 5, resulting in 59/40, roughly 1.5”.
Re:Perseverance Rover lands on Mars [video] by sojournerc on Thursday February 18, 2021 @11:31PM (#26189763)
There's something just right about 1/16th of an inch. About the same as a millimeter, and easy to do math with... it is weird though 1/8th, centimeter is hard to conceive, for me anyway.

When more precision is needed, so easy to go to the 32nd

Re:Perseverance Rover lands on Mars [video] by ascorbic on Friday February 19, 2021 @01:00AM (#26190225)
All you're saying is that inches are what you're used to. Being in the UK I am familiar with both inches and mm, and mm are far easier to work with than 16ths of an inch.
Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @09:25PM (#26188796)
If working with simple units of ten is beneficial then every mission should redefine units in terms of expected velocities and vehicle size so they are optimized for the actual calculations at hand.

That's not realistic, obviously, so we just pick one. The units in the system are arbitrary, really.

In reality regardless of the system you choose every calculation is going to end up with fractions of something. You aren't just going to do it in your head.

Re:Perseverance Rover lands on Mars [video] by heisenzombie on Thursday February 18, 2021 @09:40PM (#26188918)
Physicists are quite fond of redefining units so that the constants they care about are all just 1. (https://en.wikipedia.org/wiki/Natural_units).

For example, you could define mars units where the gravitational acceleration on mars is 1. Now your velocity in freefall is just equal to the time you've been freefalling! You don't even have to do a calculation!

(note: Don't actually do this. Gravitational acceleration isn't a constant when you're doing orbital mechanics.)

Re:Perseverance Rover lands on Mars [video] by MereInterest on Saturday February 20, 2021 @08:52AM (#26204079)
The main convenience of it is when deriving formulas, rather than when applying them. With all the constants set to 1, they don't need to be tracked throughout the formula, and can be put back in at the very end by looking at the units. Sprinkle the appropriate (hbar*c) or (mu0*epsilon0) at the end, and then you get your constants back.
Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @09:57PM (#26189061)
Honestly I would expect something like that to be happening at a hardware level. The number of bits in a memory address for the ground sensing radar is very interesting. Or the algorithm to determine vehicle acceleration given the voltage reading of a solid-state sensor vs the baseline. The metric system vs the imperial system is not an interesting distinction in these contexts.
Re:Perseverance Rover lands on Mars [video] by dieortin on Thursday February 18, 2021 @08:56PM (#26188568)
It does matter. See the errors caused in the past by using the imperial system. The metric system has a number of advantages.
Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @09:23PM (#26188778)
The errors were not caused by the imperial system. The errors were caused by using the imperial system and the metric system. Specifically in expecting one system and getting the other.
Re:Perseverance Rover lands on Mars [video] by bernulli on Thursday February 18, 2021 @10:48PM (#26189435)
The thing is, though, that you have these conversions even within the imperial system (https://en.m.wikipedia.org/wiki/Imperial_units#/media/File%3...) but not within the metric system.

My experience with U.S. students is that they are having a much harder time making sense of the imperial system (that they are used to) than doing problems in metric, even though they don’t use it in everyday life.

Re:Perseverance Rover lands on Mars [video] by mulmen on Thursday February 18, 2021 @11:08PM (#26189572)
Ok, so?

First off, you linked to a list of english measures which are not used in the US. Nobody uses fathoms or barleycorns.

Here is the list of actual US customary units: https://en.m.wikipedia.org/wiki/United_States_customary_unit...

Second, none of that is relevant to landing on Mars.

The only problem space where metric has an advantage is in converting between meters, kilometers and millimeters.

That’s great, and it’s easy to learn. But it doesn’t suddenly make all problems of distance easier to solve.

If I am traveling toward Mars at 47 meters per second it doesn’t help me to know that is also .047km per second. And converting to kilometers per hour involves using base 60 twice anyway because metric time is unwieldy.

In reality none of your measurements are going to be nice round numbers. Mentally converting from meters to km might be nice sometimes but it’s essentially a party trick.

It won’t help the lander make decisions. The hardware doesn’t inherently work in base 10.

Does NASA mix meters and kilometers? Isn’t that the same problem that destroyed the Mars Climate Orbiter?

The fact is the units are irrelevant beyond just being defined and used consistently.

Also, I can’t think of a situation where I need to convert miles to feet. My bike ride is six miles, I’m never going to express that in feet. If I need to describe the size of a thing in a room I will probably use feet, maybe inches if it is small. Probably not feet and inches. I wouldn’t use miles at all. Easy conversion between those units just isn’t a problem that comes up. It’s more important to me to have reasonably sized units and that the person I am communicating with understands them.

Re:Perseverance Rover lands on Mars [video] by cambalache on Friday February 19, 2021 @12:23AM (#26190061)
Without looking could you tell me..

How many pounds does a cubic feet of water have?

How many BTUs do you need to heat 10x10x3 ft water pool 20 degrees F?

How much work in ft-lb is done by gravity when a 10 oz mass drops from 19 yards?

How many HP are needed to rais 2400 lbs 74 inches in 30 sec?

It is obvious you have 0 experience doing back-of-the-envelope calculations for scientific or engineering purposes. It is a no-contest between the metric and the imperial systems.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @12:37AM (#26190130)
I’d love to have a box of JPL envelopes so I can do calculations like a real engineer.
Re:Perseverance Rover lands on Mars [video] by lmm on Thursday February 18, 2021 @11:38PM (#26189815)
> If I am traveling toward Mars at 47 meters per second it doesn’t help me to know that is also .047km per second.

Yes it does. It means you can immediately sanity-check your numbers even if you don't have a good sense of what meters and kilometers are, because you have that base/kilo relationship.

> My bike ride is six miles, I’m never going to express that in feet.

You can eyeball how fast you're going in feet per second and have a rough idea of how long your ride is going to take. Or rather you could if you had any idea of how long your ride was in feet. There are lots of little everyday things that just become much easier.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @12:17AM (#26190028)
I’m not sure how that sanity check works, can you explain? Do you mean checking conversion between meters and kilometers? Because sure, that’s easier but you could just do everything in meters instead and not run the risk of crashing a spacecraft because of unnecessary conversions or bad assumptions.

I estimate my bike ride progress in landmarks and time. Not feet per second. Did I get to the boat ramp in 20minutes? Better speed up and get to the park by 30.

Re:Perseverance Rover lands on Mars [video] by lmm on Friday February 19, 2021 @01:35AM (#26190384)
> Do you mean checking conversion between meters and kilometers? Because sure, that’s easier but you could just do everything in meters instead and not run the risk of crashing a spacecraft because of unnecessary conversions or bad assumptions.

But you'll have small distances and large distances and pieces from external sources who use measurements on a scale that makes sense to them. You can make your external sources do conversions themselves, but that's just moving the problem around. There will usually end up being a point, or probably several points, where you have to relate a small distance to a large distance, and wherever that happens, a human sanity check is a help.

> I estimate my bike ride progress in landmarks and time. Not feet per second. Did I get to the boat ramp in 20minutes? Better speed up and get to the park by 30.

Precisely - you have no sense of the relation between your speed and how far you can go, because you're using a terrible measurement system, and you don't even notice the how that's robbing you of the ability to develop useful intuitions.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @01:58AM (#26190471)
My bicycle doesn’t even have a speedometer so I’m not sure how the metric system is supposed to expand my world. I’m happy looking around and glancing at my watch.

Miles per hour is literally a measure of distance over time. If I wanted to use my GPS I could very easily determine how far I can go in a given amount of time. I can do this equally well in the metric or imperial systems, without converting to feet or meters.

Re:Perseverance Rover lands on Mars [video] by lmm on Sunday February 21, 2021 @04:10AM (#26212042)
Do you never ride somewhere where you don't know how far apart everything is beforehand? I can eyeball 100/200/300m and add those up into km. I could probably learn to eyeball 100/200/300 yards, but forget relating that to miles.
Re:Perseverance Rover lands on Mars [video] by bernulli on Friday February 19, 2021 @12:03AM (#26189956)
Yes I understand. Imperial is awesome because you can divide a foot by exactly 2, 3, 4 , and 6, which of course, is the main problem everyone has every day. Metric on the other hand sucks because none of my measurements will ever be nice round numbers.

The hardware doesn’t think in base 10, but having more than that in imperial makes it better?

Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.

If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @12:13AM (#26190013)
> Yes I understand. Imperial is awesome because you can divide a foot by exactly 2, 3, 4 , and 6, which of course, is the main problem everyone has every day.

Great, we agree.

> Metric on the other hand sucks because none of my measurements will ever be nice round numbers.

Depends on the situation. Metric units can be useful.

> The hardware doesn’t think in base 10, but having more than that in imperial makes it better?

No, it means neither system has an advantage so just pick one. Or invent a new one that allows better hardware utilization.

> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.

I don’t convert, I just pick the unit that fits the problem.

> If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.

Yeah I use the metric system all the time. Just like NASA.

Re:Perseverance Rover lands on Mars [video] by bernulli on Friday February 19, 2021 @11:22AM (#26194699)
>> The hardware doesn’t think in base 10, but having more than that in imperial makes it better? >No, it means neither system has an advantage so just pick one. Or invent a new one that allows better hardware utilization.

But one of the systems does have an advantage because it stays in base 10, whereas the other doesn't.

>> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion. >I don’t convert, I just pick the unit that fits the problem

But you can't if you just use the `intuitive unit', and that's the whole problem. How would you measure the amount of liquid fuel in, say, the small tank for an attitude control thruster of some probe? How does that add to the overall mass of the whole probe? Or to the force you then need to accelerate it by a certain amount? And now compared to the whole launcher?

In which units do you measure everything going on in a small wind tunnel model, and how do you compare that with the real thing?

Under which conditions do you go from fluid ounces to ounces to cups to pints to quarts to gallons (also note that, again, you not only switch units but bases)?

>Yeah I use the metric system all the time. Just like NASA.

Good for you, it solves all the problems.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @02:31PM (#26197009)
> But one of the systems does have an advantage because it stays in base 10, whereas the other doesn't.

That's a benefit to humans, not to hardware, which was the context in which I was speaking.

> But you can't if you just use the `intuitive unit', and that's the whole problem. How would you measure the amount of liquid fuel in, say, the small tank for an attitude control thruster of some probe? How does that add to the overall mass of the whole probe? Or to the force you then need to accelerate it by a certain amount? And now compared to the whole launcher?

Honestly? I'd probably measure it in volts. That's what the hardware is doing after all. That's my point, it doesn't help the computer to convert to base 10 and do calculations that way. Fuel level is measured in volts using binary. For a human something like grams probably makes more sense so sure, display it in those units. But that's a conversion.

> In which units do you measure everything going on in a small wind tunnel model, and how do you compare that with the real thing?

Again, volts on strain sensors. Maybe analog or maybe binary, in newtons. Again, the hardware doesn't think in units humans prefer. There has to be a conversion that doesn't use simple in-your-head math.

> Under which conditions do you go from fluid ounces to ounces to cups to pints to quarts to gallons (also note that, again, you not only switch units but bases)?

Cups, pints, quarts and gallons are all based on the ounce and powers of two. A gallon is 128oz, a half gallon is 64oz, a quart is 1/2 of a half gallon (or a quarter gallon) or 32oz (also, approximately a liter). A pint is half a quart or 1/8th of a gallon or 16oz, a cup is half a pint or 1/16th of a gallon or 8 oz. These fractional scales are really handy for converting between units in some situations. The unit fits the task at hand or you can trivially double or halve the size of the unit if needed. It's the same fractional scale and math used with the inch.

Re:Perseverance Rover lands on Mars [video] by bernulli on Saturday February 20, 2021 @11:23AM (#26205281)
Frankly, I can't even tell if you're just being sarcastic at this point.
Re:Perseverance Rover lands on Mars [video] by mulmen on Saturday February 20, 2021 @04:19PM (#26208088)
I'm not being sarcastic.

I have gone much farther here than I normally would. I don't think I can constructively explain this to you any further.

Re:Perseverance Rover lands on Mars [video] by jerven on Friday February 19, 2021 @05:35AM (#26191571)
I just want to add. It's quite common in carpentry to work with 120cm base wood. Which devides just as nice. And even then it's easier to convert when moving into bigger or smaller units.
Re:Perseverance Rover lands on Mars [video] by zajio1am on Friday February 19, 2021 @09:54AM (#26193774)
>The errors were caused by using the imperial system and the metric system

Using one universally accepted system is core idea behind metric system. Now, it looks like it is competition between two equal systems, but historically it is competition between ideas 'we should have one universal system' and 'every country/area can stay on their local systems'. Just all other legacy local systems (outside u.s. customary) disappeared.

Re:Perseverance Rover lands on Mars [video] by Cthulhu_ on Friday February 19, 2021 @05:33AM (#26191563)
Quick, how many miles is 26357 feet?

With metric it's a matter of shifting the decimal.

How much is a sixteenth inch anyways.

Re:Perseverance Rover lands on Mars [video] by mulmen on Friday February 19, 2021 @03:05PM (#26197438)
Yes, conversion between mm, cm, m and km is easy. What's your point? If something is miles away why do I care about it in terms of feet? How many meters is the sun from here? How many km is 1/3 of an AU? How many seconds does it take light to go a meter in vacuum?

A 16th is half an 8th. Twice as much as a 32nd. AKA 2^4, 2^3 and 2^5, respectively.

Re:Perseverance Rover lands on Mars [video] by lmilcin on Thursday February 18, 2021 @07:06PM (#26187660)
Actually, NASA uses metric system internally. Imperial units are probably used for general public convenience.
Re:Perseverance Rover lands on Mars [video] by spaetzleesser on Thursday February 18, 2021 @11:24PM (#26189704)
Considering that one of NASA's roles is to inspire young people to enter STEM I think it would be important to promote metric as much as possible.
Re:Perseverance Rover lands on Mars [video] by lmilcin on Friday February 19, 2021 @05:23AM (#26191487)
I don't see how the choice here can promote STEM.

Do you think kids find it sexy to talk about meters, kilograms and degrees Celcius rather than feet, miles, pounds and Fahrenheit?

I can't fault for choosing what is more understandable to the target audience.

Re:Perseverance Rover lands on Mars [video] by fckthisguy on Thursday February 18, 2021 @07:40PM (#26187949)
As another commenter said, NASA uses metric.

During the stream, you can hear the various teams giving measurements in metric, whilst the media gave coverage in imperial.

It's a pretty interesting video from that perspective, as you can hear the two "realities" being translated for the intended audience.

Re:Perseverance Rover lands on Mars [video] by dmix on Thursday February 18, 2021 @06:36PM (#26187374)
> And read about how it will use Terrain Relative Navigation to find a safe landing spot:

So basically TERCOM from cruise missles but used on space crafts? All you need is a radar countour map of the area and it can automate it's way to the endzone.

https://en.wikipedia.org/wiki/TERCOM

Re:Perseverance Rover lands on Mars [video] by FredFS456 on Thursday February 18, 2021 @11:23PM (#26189696)
Perseverance's Terrain Relative Navigation uses a camera system and generates a full 3D position fix, but the idea is similar.
Re:Perseverance Rover lands on Mars [video] by gnzoidberg on Wednesday February 24, 2021 @01:34AM (#26247249)
Not at all.
Re:Perseverance Rover lands on Mars [video] by koheripbal on Thursday February 18, 2021 @05:31PM (#26186690)
Any idea when they will start experimentation? I want to find microbial life!
Re:Perseverance Rover lands on Mars [video] by Nzen on Thursday February 18, 2021 @08:32PM (#26188368)
I don't know in general, but JPL published a video [0] yesterday of three interviews. One of the systems engineers for the MOXIE (atmospheric oxygen separation) unit will wait several weeks after landing before their first experiment. Actually, scientific american has published a timeline that seems to corroborate that [1].

[0] https://youtu.be/TUd604rBR6I?t=643

[1] https://www.scientificamerican.com/article/the-first-100-day...

Re:Perseverance Rover lands on Mars [video] by frabbit on Thursday February 18, 2021 @09:22PM (#26188769)
What is it about that that excites you so much?

Is it the idea that life could originate elsewhere and that there might really be aliens?

Or is it the idea that Mars could support some sort of colony?

Or the hope of completely novel microbiology?

Re:Perseverance Rover lands on Mars [video] by yellowapple on Thursday February 18, 2021 @10:01PM (#26189091)
Yes.

Any one of these things would be a massive boon to our understanding of life throughout the solar system and broader universe, right down even to here on Earth. All three of them would arguably mark a new era in Earth's history.

Re:Perseverance Rover lands on Mars [video] by cdelsolar on Friday February 19, 2021 @12:07AM (#26189983)
we are very screwed if they find life on Mars. It means life is incredibly common and thus the Great Filter theory is true and we only have a few years left as a species most likely.
Re:Perseverance Rover lands on Mars [video] by JohnJamesRambo on Friday February 19, 2021 @12:18AM (#26190038)
I find it extremely hard to believe you could kill every human being on earth at this point. We’ve reached critical mass, we aren’t going anywhere. When we had that few thousand individuals population bottleneck in the past was when it was dicey. What sort of event could kill every human and end our species? I can only think of planet-wide extinction events like massive asteroid impacts that sterilized the whole earth. And we haven’t ever had one of those in billions of years. Call me too optimistic but I think humans are too resourceful. Some of us would survive anything smaller.
Re:Perseverance Rover lands on Mars [video] by mongol on Friday February 19, 2021 @01:59AM (#26190479)
I wonder what a huge Carrington solar storm would do to humanity. If electricity went out everywhere, transformers burned up all over, electronics fried. If this caused transport failures, mass starvation could follow. I really hope a severe solar storm would not be as bad as that and hopefully someone could enlighten me on this.
Re:Perseverance Rover lands on Mars [video] by yellowapple on Saturday February 20, 2021 @04:46PM (#26208268)
> If this caused transport failures, mass starvation could follow.

The good news is that a substantial chunk of the world's cargo transportation runs on diesel (or other combustion setups similarly not reliant on electronics), so in a pinch it could probably keep going. Same with agricultural machinery. Might need to replace or refurbish some ECUs, but I'm sure there are enough clever mechanics out there willing and able to bypass those in an emergency that we'd be back up and running pretty quick on that front.

ICE 1, electric 0 ;)

It's refrigeration that'd have me more concerned, since pretty much all modern refrigeration is electrically powered (last I checked). Diesel generators might come in clutch there, assuming the refrigeration units themselves don't rely on any fancy electronics.

Re:Perseverance Rover lands on Mars [video] by throwaway0a5e on Friday February 19, 2021 @09:01AM (#26193201)
>I wonder what a huge Carrington solar storm would do to humanity

Worst case it sets us back to 1870ish, maybe. Depends on how fast things go to crap vs how fast things can be rebuilt.

Likely case you'd basically get a "purge" because society as we know it can't keep on rolling with the kind of economic breakdown something like that would cause so there's be a lot of dying in the interim but if you don't starve or get shot in the first 6mo you're probably good with the very old, very young and unproductive bearing the brunt of it (same as every other disaster) It would be like the black death, but global and all at once. Balance of power globally would definitely be altered in unforeseeable ways but the overall net result is things would bounce back hard.

Re:Perseverance Rover lands on Mars [video] by saagarjha on Friday February 19, 2021 @04:19AM (#26191135)
Killing literally every single human being is not easy. Sure, killing off half of humanity is pretty easy to conceive, but to kill all of humanity it takes a lot more work.
Re:Perseverance Rover lands on Mars [video] by xaqfox on Friday February 19, 2021 @10:34AM (#26194214)
Luckily, we have great minds working on this problem: https://www.appliedeschatology.com/
Re:Perseverance Rover lands on Mars [video] by sjy on Friday February 19, 2021 @05:34PM (#26198922)
There have been at least five mass extinction events in the last 500 million years. The most recent one wiped out all non-avian dinosaurs, after they had dominated the earth for 100 million years. Tool-using apes with language have been around for less than 5 million. I think it’s far too early to say we’ll survive the next extinction event, or even make it that far before diverging into new species.
Re:Perseverance Rover lands on Mars [video] by yellowapple on Friday February 19, 2021 @01:09AM (#26190265)
> When we had that few thousand individuals population bottleneck in the past was when it was dicey.

Yeah, but those individuals were presumably all in pretty close proximity to one another. If we were left with a few thousand individuals across the entire range of the human-inhabited Earth, we'd have one heck of a time continuing as a species.

In any case, the risk of an extinction event on Earth is exactly why I believe space colonization needs to be Priority Zero for humanity, from two different angles:

1. Living beyond Earth means that we as a species are that much more resilient against a literal-Earth-shattering catastrophe (and if we can get the bulk of Earth's current/future population off of Earth, then we might very well be able to avoid a couple different plausible extinction events).

2. If we can colonize entirely inhospitable worlds like Mars or the Moon (or my votes, Ceres, Venus, and Enceladus), then "colonizing" Earth is easy-peasy-lemon-squeezy even if it does become Venus 2: Greenhouse Boogaloo.

Re:Perseverance Rover lands on Mars [video] by DowsingSpoon on Friday February 19, 2021 @03:46AM (#26190949)
Disagree. If there is a filter at all then it could easily be that we’ve already passed it. Maybe the filter is the formation of multicellular life, for example. Also, Earth and Mars have exchanged a lot of material. If we find Mars life, it would not at all be surprising to learn it is related to Earth life.
Re:Perseverance Rover lands on Mars [video] by koheripbal on Sunday February 21, 2021 @09:54AM (#26213843)
It's hard to imagine that the change from unicellular life to multicellular life is a great filter. Even single cell life has evolved to crazy complexity that blurs the lines between single and multicellular life.

> If we find Mars life, it would not at all be surprising to learn it is related to Earth life.

If it's DNA/RNA based, we might actually be able to determine the relationship and whether that's true or not.

Re:Perseverance Rover lands on Mars [video] by ericbarrett on Saturday February 20, 2021 @04:02AM (#26202794)
Earth is pretty special. We’ve got a big ol’ moon (seriously, the Moon is huge for a planet our size), Jupiter running interference for us with its massive gravity and incomprehensible magnetic field, our host star is very polite, we’ve even got a magnetic field AND ozone layer on the planet itself. Not to mention it’s kept life going for 30% of the age of the universe. It’s a good CV for Great Filter applications.
Re:Perseverance Rover lands on Mars [video] by yellowapple on Friday February 19, 2021 @01:04AM (#26190243)
> and thus the Great Filter theory is true

Or we're just ahead of the curve.

Re:Perseverance Rover lands on Mars [video] by russtrotter on Thursday February 18, 2021 @10:05PM (#26189126)
Some interesting reasons: the proverbial "2nd genesis", panspermia possibilities of our own planet, and answering lots of questions on formation of life on ours and any other planet we might encounter.
Re:Perseverance Rover lands on Mars [video] by nerfhammer on Friday February 19, 2021 @04:04PM (#26198012)